How do you blow a 3-0 lead? How do you do it with Landon Donovan, David Beckham and Robbie Keane on your side, not to mention Omar Gonzalez, the MLS Defender of the Year in 2011?

As wary as anyone can be, the Galaxy take to CenturyLink Field in Seattle tonight hugging a three-goal advantage in the home-and-home Western Conference finals.

Limit the Sounders to two goals or fewer, and it’s on to a second consecutive MLS Cup for the defending champions.

But all the talk of defending might be a little offensive to the Galaxy, who took on an aura of former NFL coach Herman Edwards and his “You play to win the game” rant.

“I didn’t grow up as a defender, so I’m not going to defend for 90 minutes,” Galaxy captain Landon Donovan said. “I’m going there to try to do my part to help us defend, but I’m going there to score goals and make plays. And Robbie’s the same, Mike Magee’s the same, and David’s the same.”

Against a team that finished ahead of the Galaxy in the regular season, with their own offensive stars like Eddie Johnson, Fredy Montero and Mauro Rosales, Seattle will be buoyed by a home crowd that could reach 60,000.

And MLS history has one glaring cautionary tale of how not to approach an aggregate-goals series.

In 2003, the Galaxy scored a 2-0 win at home, then went to San Jose and took a 2-0 lead for a 4-0 aggregate advantage. San Jose, with Donovan in the middle, promptly scored four times to tie it and scored against in overtime to complete the rally/choke.

“It was a crazy game,” Donovan said. “It teaches you that in this sport, as much as any, anything can happen. In that game L.A., after they scored a couple goals, kind of went into a defensive shell and that’s not something we’re going to do.

“Our intention is to go there and win the game. We’re not going there to lose by a goal or lose by two goals or tie the game.”

The Galaxy are expecting a cold, rainy day surrounded by a hostile crowd on a field that has dealt them some unkind defeats. There was a penalty kick shootout loss to Real Salt Lake in 2009 and 2-0 and 4-0 defeats there earlier this season.

The Galaxy offense is on fire – Keane has scored four goals in the last two games and Magee has added the other two – but they have enough to be concerned about.

Beckham trained on Friday but played through a cold that knocked his voice seemingly an octave lower than normal. Donovan has a tight hamstring that could be bad enough to prevent him from playing.

The Galaxy have no idea if midfielder Juninho (Achilles’ inflammation) will be ready. The same goes for forward Edson Buddle (plantar inflammation).

But they do know they’re ready to push the envelope to reach the eighth MLS Cup in franchise history.

“If we say, `Let’s play it safe’ and not play myself or Juni or Edson or anybody, you might be out of it and the season’s over,” Donovan said. “I’d much rather put myself on the line a little bit and make sure that we advance and you can worry about the rest later.”

As much as the physical matters in the game, the Galaxy will rely on their mental capacities with a veteran club.

Part of that means embracing exactly where the club stands, and not trying to fabricate scenarios for inspiration.